Engineering
Physics
Relative Motion
Question

Airplanes A and B are flying with constant velocity in the same vertical plane at angles 30° and 60° with respect to the horizontal respectively as shown in figure. The speed of A is 1003ms1. At time t = 0s, an observer in A finds B at a distance of 500 m. This observer sees B moving with a constant velocity perpendicular to the line of motion of A. If at t = t0, A just escapes being hit by B, t0 in seconds is :

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Solution

 VBA=VBVA

⇒ v cos 30° =1003

⇒ v = 200 m/s

 VBA = v sin 30° = 100 m/s

  t = SBA/VBA = 5 sec.